Subject: Comments/Questions on STUN, Request for submissions

From: alan bartky <[email-masked]>
Date: Tue, 13 Jul 93 11:00:33 PDT

Having read Wayne Clark's contribution on STUN I have the following comments
and questions.

It looks like a much simpler protocol as far as handling SDLC to SDLC 
connections across an IP network, using TCP as an error corrected sequenced
protocol so that SDLC can be locally acknowledged (so you don't have to
poll through the network).  I think it would be interesting to know about
it's advantages and disadvanteges compared with DLSw.  Here are some
questions I have:

1) Is STUN used for SNA LLC2 to LLC2 connections.  If so, how does it work?
If not, what is used instead?

2) Is STUN used for SNA SDLC to SNA LLC2 connections (e.g SDLC controller
communicating with remote Token Ring Attached host).  If so, how does it
work?  If not, what is used instead?

3) Is STUN used for NETBIOS?  Is so, how does it work?  If not, what is
used instead?

I think that I would like to see more about the STUN protocol (Thanks Wayne
for the contribution) and would like some comments and questions from other
members.  I am also sure that the different router vendors have other methods
of supporting SNA/SDLC, SNA/LLC2, and NETBIOS.  Let's get some contributions
in this week so we can start working towards a common method between all
the vendors for these protocols.

Alan K. Bartky
Chair, Connect SIGlet.

P.S.  I don't have a name yet for an Active Member from IBM.

---

From: [email-masked]
Date: Tue, 13 Jul 93 11:31:28 PDT

Alan, et.al. -

    I've include my replies below.

Wayne

>If not, what is used instead?

    STUN is used only for SDLC-to-SDLC traffic.  This is partly historical
    and partly technical.  The technical reason is that any individual
    router supports only a limited number of SDLC connections (generally,
    1 serial port = 1 SDLC link station) and the ability to equate a single
    SDLC link station to a single TCP/IP session greatly simplifies
    the logic.

    This requirement doesn't hold for LLC2-to-LLC2 since 1 LAN port = n LLC2
    link stations so the decision was made to multiplex LLC2 session traffic
    to keep the number of TCP/IP sessions in the router from exploding.  We
    call the LLC2-to-LLC2 tunneling product RSRB for Remote Source Route
    Bridging.

>work?  If not, what is used instead?

    We use the RSRB tunnel for SDLC-to-LLC2 traffic.  Agruably, we could
    have gone either way but the developer who did the SDLC-to-LLC2 feature
    was more comfortable with RSRB than STUN.  We have talked about replacing
    the SDLC-to-LLC2 tunnel with STUN's single TCP/IP session logic but
    this falls under the category of "creeping elegance".  There has never
    been a customer request for it and the multiplexing overhead isn't
    that much.

>3) Is STUN used for NETBIOS?  Is so, how does it work?  If not, what is

    RSRB is used for NetBIOS (because of the LLC2-to-LLC2 requirement above).